-LRB- CNN -RRB- -- World Anti-Doping Agency -LRB- WADA -RRB- president John Fahey has told CNN he does n't think Novak Djokovic `` has the faintest idea '' what his organization does after the former world No. 1 said he 'd lost faith in the system .

The Serbian labeled compatriot Viktor Troicki 's 12-month ban from tennis for missing a drugs test a `` total injustice '' and said he was now nervous to give any sort of sample .

But Fahey dismissed the six-time grand slam winner 's comments as unhelpful and said it was up to the sport to do more to fight against doping .

`` I do n't think Novak Djokovic has the faintest idea what we do and if he wants to understand what we do I 'm more than happy to pick up the phone and talk to him , if he wants to talk to me , '' he told CNN .

`` If he wishes to then make a comment I might listen to him but for the moment I do n't think that was an informed statement . ''

WADA 's role in the fight against doping in sport has been in the spotlight in recent months after a string of athletes failed tests in Kenya and Jamaica .

And as well as Troicki , Croatian tennis star Marin Cilic also served a ban for doping offenses after taking a prohibited substance contained in supplements bought from a chemist .

Those cases have provoked disagreement within the game as to the best course of action , with Wimbledon champion Andy Murray calling the pair 's actions `` unprofessional . ''

Roger Federer , winner of 17 grand slams , said more testing needed to be done within the sport and also said players should give a sample when requested .

But when asked if he knew how widespread doping in tennis was , Fahey replied : `` No I do n't and nor do I think tennis knows how widespread it is .

`` What I do know is they have a program and a commitment has been given . Can they do more ? Every sport can do more .

`` And when you get criticism from some of the champion tennis players about the number of times they 've been tested then I hope tennis takes notice of it . I know they have and I believe that they 'll address it . ''

Fahey also said the fall from grace of cyclist Lance Armstrong had been the best anti-doping message since he became WADA president in 2007 .

In January , Armstrong -- following years of strenuous denials -- admitted to doping throughout his storied career , after he had been stripped of his seven Tour de France titles .

But Fahey thinks Armstrong 's descent has proved that drug cheats will be caught out and punished no matter what their status .

`` I think the Lance Armstrong story was the best message in my six years as to the effectiveness of the anti-doping programs , '' he explained .

`` What that said to me and the rest of the world was no matter how big you are , how tall , how successful you are , you can get caught and be dealt with . That man has been destroyed in terms of reputation and in terms of , perhaps , many other aspects of his life .

`` He 's been seen as a cheat , a bully , a liar -- there 's no doubt about that . Once upon a time he was revered as one of the greatest champions in his sport , of all time .

`` The fact that someone as big as that is ultimately brought to justice shows that our code is effective . ''

As for athletics , Fahey acknowledged that doping is `` widespread '' and said part of the reason might be that there are different resources available to tackle the problem in different countries .

Kenya has had 17 athletes banned for doping offenses since 2012 , while former 100 meters world record-holder Asafa Powell and three-time Olympic gold medalist Veronica Campbell-Brown are among six Jamaicans to have tested positive this year .

Fahey said doping is not just a problem in successful sporting countries like Kenya and Jamaica , but rejected the notion performance-enhancing drugs were beginning to ruin sport .

There had been a suggestion that certain countries could be banned from the Olympics if they refused to comply with anti-doping programs -- raising the prospect of Jamaica 's six-time Olympic champion Usain Bolt missing out -- but Fahey said that was for the International Olympic Committee to determine .

`` Should the Iinternational Olympic Committee take stronger steps ? I 'm sure if the evidence is there on the basis of difficulties with compliance in any particular country they would look seriously at that , '' he said .

`` I think we have to stop for a moment and say , ` What is actually going on in Jamaica ? ' They do have an anti-doping program , it has not been effective , it has not been as good as it could have been and that 's what WADA examined .

`` We now have given them recommendations and we 've got a commitment to say , ` Yes we dropped the ball but we 've picked it up again and we 'll get it right and we 'll do that quickly . ' ''

Fahey also said that WADA 's revised code , which is due out this week , would allow the agency greater investigative powers and called it a `` great jump forward . ''

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WADA president John Fahey replies to Novak Djokovic 's criticism

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World No. 2 tennis star said he 'd lost faith in agency after Viktor Troicki 's ban

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Fahey tells CNN that Djokovic `` has n't got the faintest idea what we do ''

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He says Lance Armstrong case shows that no-one is above the regulations